The Dangers of Hypnotism.-Much has been written on this head of late years, and some of the enthusiastic advocates of hypnotic treatment have done harm to their cause by ignoring or denying in a too thoroughgoing manner the possibility of undesirable results of the spread of the knowledge and practice of hypnotism. Like all powerful agencies, chloroform or morphia, dynamite or strong electric currents, hypnotic suggestion can only be safely used by those who have special knowledge and experience, and, like them, it is liable to abuse. There is little doubt that, if a subject is repeatedly hypnotized and made to entertain all kinds of absurd delusions and to carry out very frequently posthypnotic suggestions, he may be liable to some ill-defined harm; also, that an unprincipled hypnotize might secure an undue influence over a naturally weak subject. But there is no ground for the belief that hypnotic treatment, applied with good intentions and reasonable care and judgment, does or can produce deleterious effects, such as weakening of the will or liability to fall spontaneously into hypnosis. All physicians of large experience in hypnotic practice are in agreement in respect to this point. But some difference of opinion exists as to the possibility of deliberately inducing a subject to commit improper or criminal actions during hypnosis or by posthypnotic suggestion. There is, however, no doubt that subjects retain even in deep hypnosis a very considerable power of resistance to any suggestion that is repugnant to their moral nature; and it has been shown that, on some cases in which a subject in hypnosis is made to perform some ostensibly criminal action, such as firing an unloaded pistol at a bystander or putting poison into a cup for him to drink, he is aware, however obscurely, of the unreal nature of the situation. Nevertheless it must be admitted that a person lacking in moral sentiments might be induced to commit actions from which in the normal state he would abstain, if only from fear of punishment; and it is probable that a skilful and evil-intentioned operator could in some cases so deceive a well disposed subject as to lead him into wrong-doing. The proper precaution against such dangers is legislative regulation of the practice of hypnotism such as is already enforced in some countries.
Bibliography.—The literature of hypnotism has increased in volume at a rapid rate during recent years. Of recent writings the following may be mentioned as amon the most important:—Treatment by Hypnotism and Suggestion by C. Lloyd Tuckey, M.D. (5th ed., London, 1907); Hypnotism, its History, Practice and Theory, by J. Milne Bramwell, M.B. (2nd ed., London, 1906); Hypnotism, by Albert Moll (5th ed., London, 190r). All these three books give good general accounts of hypnotism, the first being the most strictly medical, the last the most general in its treatment. See also Hypnotism: or Suggestion in Psycho-Therapy, by August Forel (translated from the 5th German ed. by G. H. W. Armit, London, 1906); a number of papers by Ed. Gurney, and by Ed. Gurney and Myers in Proc. of the Soc. for Psychical Research, especially “ The Stages of Hypnotism," in vol. ii.; also some more recent papers in the same journal by other hands; chapter on Hypnotism in Human Personality and its Survival of bodily Death, by F. W. H. Myers (London, 1903); The Psychology of Suggestion, by Boris Sidis, Ph.D, (New York, 1898); “ Zur Psychologie der Suggestion," by Prof. Th. Lipp, and other papers in the Zeitschrift for Hypnotismus. Of special historical interest are the following:—Étude sur le zoomagnétisme, par A. A. Liébeault (Paris, 1883); Hypnotisme, suggestion, psycho-thérapie, par Prof. Bernheim (Paris, 1891); Braid on Hypnotism (a new issue of James Braid's Neurypnology), edited by A. E. Waite (London, 1899); Traité du somnambulism, by A. Bertrand (Paris, 1826). A full bibliography is appended to Dr Milne Bramwell's Hypnotism. (W. McD.)
HYPOCAUST (Gr. ὑπόκαυστον: ὑπό, beneath, καυείν to burn), the term given to the chamber formed under the floors of the Roman baths, through which the hot air from the furnace passed, sometimes to a single flue, as in the case of the tepidarium, but in the calidarium and sweating-room to a series of flues placed side by side forming the lining of the walls. The floor of the hot-air chamber consisted of tiles, 2 ft. square, laid on a bed of concrete; on this a series of dwarf piers 2 ft. high were built of 8-in. square tiles placed about 16 in. apart, which carried the floor of the hall or room; this floor was formed of a bed of concrete covered with layers of pounded bricks and marble cement, on which the marble pavement in slabs or tesserae was laid. In colder countries, as for instance in Germany and England, the living rooms were all heated in a similar way, and round Trèves (Trier) both systems have been found in two or three Roman villas, with the one flue for the ordinary rooms and several wall flues for the hot baths. In England these hypocausts are found in every Roman settle merit, and the chief interest in these is centred in the magnificent mosaic pavements with which the principal rooms were laid. Many of the pavements found in London and elsewhere have been preserved in the British or the Guildhall museums; and in some of the provincial towns, such as Leicester and Lincoln, they remain in situ many feet below the present level of the town.
HYPOCHONDRIASIS (synonyms— "the spleen," "the vapours"), a medical term (from τὸ ὑποχόνδριον, τὰ ὑποχόνδρια, the soft part of the body immediately under the χόνδρος or cartilage of the breast-bone) given by the ancients,and indeed by physicians down to the time of William Cullen, to diseases or derangements of one or more of the abdominal viscera. Cullen (Clinical Lectures, 1777) classified it amongst nervous diseases, and Jean Pierre Falret (1794–1870) more fully described it as a morbid condition of the nervous system characterized by depression of feeling and false beliefs as to an impaired state of the health. The subjects of hypochondriasis are for the most part members of families in which hereditary predisposition to degradation of the nervous system is strong, or those who have suffered from morbid influences affecting this system during the earlier years of life. It may be dependent on depressing disease affecting the general system, but under such circumstances it is generally so complicated with the symptoms of hysteria as to render differentiation difficult (see Hysteria). Hypochondriasis is often handed down from one generation to another in its individual form, but it is also not unfrequently to be met with in an individual as the sole manifestation in him of a family tendency to insanity. In its most common form it is manifested by simple false belief as to the state of the health, the intellect being otherwise unaffected. We may instance the " vapourish " woman or the " splenetic " as terms society has applied to its milder manifestations. Such persons are constantly asserting a weak state of health although no palpable cause can be discovered. In its more definite phases pain or uneasy sensations are referred by the patient to some particular region, generally the abdomen, the heart or the head. That these are subjective is apparent from the fact that the general health is good: all the functions of the various systems are duly performed; the patient eats and sleeps well; and, when any circumstance temporarily overrides the false belief, he is happy and comfortable. No appeal to the reason is of any avail, and the hypochondriac idea so dominates his existence as to render him unable to perform the ordinary duties of life. In its most aggravated form hypochondriasis amounts to actual insanity, delusions arising as to the existence of living creatures in the intestines or brain, or to the effect that the body is materially changed; e.g. into glass, wood, &c. The symptoms of this condition may be remittent; they may even disappear for years, and only return on the advent of some exciting cause. Suicide is occasionally committed in order to escape from the constant misery. Recovery can only be looked for by placing the patient under such morally hygienic conditions as may help to turn his mind to other matters. (See also Neuropathology.)
HYPOCRISY, pretence, or false assumption of a high character, especially in regard to religious belief or practice. The Greek ὑπόκρισις, from which the word is derived through the Old French, meant primarily the acting of a part on the stage, from ὑποκρίνεσθαι, to give an answer, to speak dialogue, play a part on the stage, hence to practice dissimulation.
HYPOSTASIS, in theology, a term frequently occurring in the Trinitarian controversies of the 4th and 5th centuries. According to Irenaeus (i. 5, 4) it was introduced into theology by Gnostic writers, and in earliest ecclesiastical usage appears, as among the Stoics, to have been synonymous with oboia. Thus Dionysius of Rome (cf. Routh, Rel. Sacr. iii. 373) condemns the attempt to sever the Godhead into three separate hypostases and three
deities, and the Nicene Creed in the anathemas speaks of